Gas detectors for sensing halogenated gases and other gases by the effects of such gases on the electrical properties of certain materials are known. Gas detectors of this type include those described in the following patents: Loh et al. U.S. Pat. No. 3,751,968 entitled "Solid State Sensor", Loh U.S. Pat. No. 4,045,729 entitled "Gas Detector" and Lee et al. U.S. Pat. No. 5,104,513 entitled "Gas Sensor". Common to all of these patents are a helical coil and pin positioned within the coil spaced from each other by a material that changes electrical resistance, as measured by change in current or voltage, when in the presence of the gas to be detected.
The industry is constantly striving for improvements in this type of detector, particularly in sensitivity to refrigerant vapors, life, power consumption and cost. It is very important that the detector must detect refrigerant vapors of the R-134a, R-12 and R-22 types.
It is an advantage, according to this invention, to provide a thermally efficient gas detector that consumes less power than prior gas detectors, thus extending battery life.
It is another advantage, according to this invention, to provide a gas detector that operates at a higher voltage and thus a lower current draw on the battery.
It is a further advantage, according to this invention, to provide a gas detector that is substantially silica free.
It is a yet further advantage, according to this invention, to provide a gas detector that is easy to manufacture.